Lubricating oil and process of producing same



Patented 'Aug'. 18, 1925.

v auulrlz'ofs'm arss'; PATENT OFFICE.

"WARREN r. rAnAennn AND ROBERT w. HENRY,- or m'rrsnunen, ANn WILLIAM A.

GRUSE, or WILKINSBURG, PENNSYLVANIA, ASSIGNORS 'ro GULF REFINING coma:-

PANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF TEXAS.

LUBRIGATING OIL AND PROCESS OE PRODUCING S AME.

No Drawing.

To all whom it may concern."

Be it known that we, WARREN F. FARA- GEER, ROBERT W. HENRY, and WILLIAM A.

GRUsE, citizens of the United States, said 'FARAGHER and said HENRY residing at Pittsand'processes of producing the same; and

it comprises an improved lubricating oil of thetypejsometimes known as mineral castor comprising a mineral lubricating oi1 containing a certain amount of a dissolved or dispersed basic aluminum oleate (palm1- tates and soaps of similar fatty acids may be used), the amount of oleic or other fatty acids in combination with aluminum being less than that necessary to form 'an' usually conaluminum dioleate; and being h ft y erema er siderably less; all as more fu set forth and as claimed. v

For the manufacture of what are known as mineral castor oils or caster machine oils, it is customary to thicken mineral lubricating oils by an addition of a certain amount of aluminum oleate. The oleate goes into solution or dispersed form and gives a great increase in viscosity. With the commercial forms of oleate usually employed, this increase is neither regular nor constant. In adding a given quantity of oleate to a given oil, the exact increase in viscosity is uncertain and the viscosity just after incorporation is by no means what it is after the thickened oil has beenallowed to stand for a time and age. There is always a marked drop in viscosity.

The oleate used is usually, if not invariably, produced by double decomposition of sodium oleate (the soda soap of oleic acid) with aluminum sulfate; aluminum sulfate being added to a water solution of the soda soap in a mixingkettle. This (gives a precipitate of aluminum oleate an a solution of sodium sulfate. The oleate is washed and dried and is then added to the oil to be thickened. Prior-to complete drying, a

a certain amount of oil is often added to give a better terial an hysical character to the dry ml make it easier to handle.

Application fi led m v, 1924. Serial No. 726,629.

The material formed in this way is usually somewhere between aluminum dioleate and trioleate; that is, between AlX OI-I and AlX -X representing a molecule of oleic acid, (3 11 00 Whether any actual trioleate is formed is not definitely known, but the commercial materials made in this way and used in thickening oils have a molecular ratio of X (oleic acid) to Al greater than 2: 1, and usually materially greater.

In making mineral castor oil with this oleate, a mineral lubricating oil is heated and the oleate stirred in until incorporation is complete. Long continued agitation and rather high temperatures are. necessary to make a smooth commercial .preparation. The amount so incorporated with the oil is varied according to the viscosity wanted.

Sometimes, the amount used is around 7 per cent. As stated, different preparations of oleate made in this way give diflerent results and in obtaining a given viscosity, diflerent proportions of different preparations must be used.

The fact that the thickened oils made with these commercial oleates do not hold a constant iviscosity from a practical point of view is-extremely inconvenient. The viscosity after standing is invariably less than that of the preparation initially made, and sometimes very much less. The drop in viscosity occurs even where the oil is in sealed containers. .The amount of drop differs with difierent preparations and is oftenquite irregular. To obtain a given final viscosity with any oil and using any particular commercial oleate is a rather empirical operation. It is customary in the art to make mineral castor oils of much higher viscosity than is ultimately wanted and. trust to the preparation dropping to a desired point in time. In so doing, it is impossible to make a standardized material.

We have found that this drop in viscosity occuring with commercial oleates is dependent upon the fact that the ratio of oleic acid to aluminum therein is higher than it should be; and that by using preparations containing less ratios of oleic acid to Al,

of our preparations, as high viscosities can be obtained with 3 per cent solutions as can be obtained with 7 per cent solutions of commercial oleates. As stated, in commercial oleates the ratio of oleic acid to Al is greater than 221 (dioleaite), sometimes going as high as 2.6: 1. Preparations having aratio less than 2:1 give better results and the ratio can be dropped to as low as 1:1 (monoleate). l/Vith monoleate, the increase in viscosity for a given addition to lubrieating oil is very much greater than with commercial oleates and with the proportions necessary to give the usual viscosities desired no decrease occurs on ageing the thickened oil; the oil is steady in this respect and steady indefinitely long. With more concentrated solution of monoleates,

ietsare further undesirable because of that is with solutions approaching the strength of those ordinarily made with commercial oleates, the viscosity instead of decreasing with age tends to increase somewhat with time. By using preparations intermediate the monoleate and the dioleate, the two tendencies, the tendency to decrease in viscosity characteristic of the dioleaites and the tendency to increase in viscosity characteristic of the monoleates balance out. The point where the mixed oleates in strong solutions give thickened oils not decreasing in viscosity with age, we have not been able to settle definitely; but it is, somewhere just below the 2: 1 ratio required for the dioleate, say around 1.7: 1 or 1.8:1.

Returning to the monoleate preparations, the viscosity they are able to confer on mineral lubricating oils, is, as stated, greater than that given by .dior tri-oleate preparations; the viscosity, as a matter of fact, being very much greater. For example, in one particular case with one particular mineral lubricating oil, a 7 per cent solution of commercial oleate pulp gave a certain viscosity after incorporation and standing; with a much higher viscosity initially. A 3 per cent solution of monoleate gave at once the same viscosity and the viscosity was steady; it did not change or diminish with time. On repeating the experiment using the same proportion of monoleate as of commercial oleate, that is, 7 per cent, the product was too viscous for commercial use.

For various purposes, we have successfully used oleates having molecular ratios all the way from between that of 1 :1 characterizing the monoleate and 1.8 1.

It is not a matter of indifference how the oleate is prepared. Aside from the fact that the products of the ordinary or standard method of making aluminum oleate, viz., reaction of sodium oleate on alumi num sulfate, cannot be made with a low oleic acid content (lower than the dioleate), whatever the proportions used, such prodtheir inconstancy of properties, chemical.

Better preparations are and physical. made by substituting aluminum acetate or aluminum chlorid for the aluminum sulfate of the standard method. But still better preparations can be made by directly combining oleic acid with precipitated gelatinous aluminum hydrate or hydrated alumina. combines readily with oleic acid; but it forfeits this property to a greater or less extent with time. In the best method of making low ratio oleates which we nowknow, we precipitate a solution of aluminum sulfate, say, of 10 per cent strength, with sodium hydrate or caustic soda, using the amount which will give a solution substantially neutral to phenolphthalein. Without troubling to wash the precipitate to get rid of mother liquor and salines (sodium sulfate) whichwould involve a delay and alteration of the properties of the alumina, we directly incorporate with it the calcu: lated amount of oleic acid; whether this ratio be the 1:1 ratio of monoleate or the somewhat higher oleic acid ratio of preparations intermediate the monoleate and dioleate. The oleic acid is added to the preparation with continuous stirring. Reaction takesplace between the hydrated alumina and the oleic acid, as evinced b a change in consistency of the mixture which becomes considerably more viscous. Toward the end of this change, we ordinarily Warm the mixture somewhat and separate the oleate from the mother liquor in any suitable way. As the material agglomerates more or less, the

Directly after precipitation, aluminamother liquor can be conveniently removed by simple drainage. After removing the mother liquor, we wash with water sufficiently to remove the sulfates present. The 7 Wet, washed alumina soap is then dried. A

convenient and advantageous way is to Sus pend it in petroleumnaphtha or any other convenient oil and subject'the mixture to heat and stirring, distilling oil the water and naphtha together. Although other ways of drying may be employed, such as the ordinary way of drying in steam jacketed kettles this way, drying in the presence of a volatile oil, gives a better product. After the bulk of the water has been removed in this or another way, drying can be completed in vacuo or in a stream of inert gas, such as nitrogen or hydrocarbon gas. Generally we do not' desire to dry to absolute dryness; finding it better to leave a. little water, say 0.3 to 0.4 per cent, or thereabouts. After drying, the oleate may be broken up or p-ulped in any mineral oil to give a standard oleate pulp.

gelatinous alumina. The method can also be applied to the manufacture of 'oleate pulps of the standard commercial types; that is, oleates having a ratio greater than 2:1. But, for reasons noted, wedo not regard these high ratio oleates as being as good for thickening oil as the low ratio oleates hereinbefore described.

What we claim is 1. A thickened mineral oil containing a basic aluminum o1eate,'the molecular ratio of oleic acid to the aluminum in such oleate being less than 2:1.

2. A thickened mineral oil containing a basic aluminum oleate, the molecular ratio of oleic acid to the aluminum in such oleate being about 1:1. 3. In the manufacture of thickened min-.

eral lubricating oils of the mineral castor type, the process which comprises directly combining freshly precipitated hydrated alumina with oleic acid, the molecular ratio of the oleic acid to the aluminum being less than 2:1 and incorporating the combined product into mineral oil.

4. In the manufacture of thickened lubrirocess which-comprises directly combining reshly precipitated hydrated aluminawit oleic acid, the molecular ratio of oleic acid eating oils of the mineral castor type, the

to the aluminum being about 1.1, and incorporating the combined product into mineral oil.

In testimony whereof, we have hereunto I 

